Power transmission



1'g. 6, 1940.- F. 1'. HARRINGTON Y 2.210,665

POWER TRANSMISSION INVENTOR FE RRIS- T. HAPRINGTON ATTORNEY le' l 2 'Sheyvts-Sheet 2 POWER TRANSMISSION v INVENTOR FERRIS T. HARRINGTON F. 'r.` HARRlNToN Filed Dec. 29, 1938v D-OZUJOW .FUJPDU Aug. 6*, 1940.

`ATTORNEY Patented Aug. 6, 1940 UNITED STATES POWER TRANSMISSION Ferris '1'. Harrington, Detroit, Mich., assigner to Vickers Incorporated, Detroit, Mich., a corporation of Michigan DEC 2 19M Application December 29, 1938, Serial No. 248,254

'z claims.

This invention relates to power transmissions, particularly to those of theV type comprising two or more fluid pressure energy translating devices one of which may function as a pump an'd another as a iiuid motor.

The invention is more particularly concerned with a power transmission system particularly adapted for actuating a reciprocating slide subject to a gravity load such as the quill of a drilling machine. l Y

It is an object of the present invention to provide a hydraulic power transmission system having improved means for preventing unwanted travel of the driven member under its gravity bias.

It is a further object to provide a system of this character wherein the control l mechanism including all necessary valves is incorporated in a single panel constructed as a three-section assembly and wherein the two outside sections containing solenoid-operated pilot valves may be selectively assembled to different center sections to provide a complete line of control panel assemblies of A various capacities. Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred form of the present invention is clearly shown.

In the drawings:

Figure 1 is a diagrammatic view of a power transmission system incorporating a preferred form of the present invention.

Figure 2 is a diagrammatic cross sectional view of a control panel forming part of the mechanism in Figure 1.

Figure 3 is a top view, Figure 4 is a front view, ,and Figure 5 is an end view of the control panel, the two side sections being displaced for clearness o! illustration, these three figures being arranged in Orthographie projection on the sheet.

Figure 6 is an end view of the backing plate for ,the control panel.

Figure 7 is a simplified diagram of the hydraulic circuit.

Figure 8 is a table of the valve positions with reference to the circuit of Figure 7. y

Referring now to Figure 1, there is shown a pump I 8 driven by a prime mover such as an electric motor I2 to withdraw uid from a tank- L6" through a suction conduit I4. Fluid is delivered through a delivery conduit I8, a relief valve 28 of conventional construction being'provided for by-passing iluid to the tank through a ret'urn conduit 22 whenever a predetermined pressure ,is exceeded in the delivery conduit I8. The delivery conduit L|8leads to a port 24 in the center section 26 of .the control panel 28. The latter has side sections 38 and 32 containing solenoid-operated pilot valves later to be described.

A port 34 in the center section 26 connects by a conduit 36 with the tank. The center section 26 is also provided with cylinder ports 38 and 40 which connect by conduits 42 and 44 with the upper and lower ends of a cylinder 46. The latter carries a slidable piston 48 having a rod 50 to which is attached the load device 52. Secured on an upwardly extending arm 54 are three tripping dogs 56, 58 and 60 adapted to actuate limit switches 62, 64 and 66 respectively when the load device 52 is at the top, mid portion, and bottom positions respectively.

For the purpose of controlling the cnergization of the solenoids in sections 30 and 32 an electric circuit is provided. A'A momentary contact push button switch 68 is adapted when depressed to connect line L1 by conductor 10 with the operating coil of a holding relay 12, the other side of which is connected to line L2. I'he holding cir- T cuit 14 extends through the normally closed contacts of a double-throw push button switch 16 and by a conductor 18 through limit switch 66 and to line L1. Thus, when the switch 68 is momentarily closed and the relay 12 is lifted, the holding circuit is established provided that the switch 16 is not depressed and limit switch 66 is in its normally closed position. Opening of either switch 16 or switch 66 will deenergize the relay 12 and permit the latter to drop. The controlled circuit of relay 12 extends from the conductor 14 through a conductor 86 to the solenoid in section 32, the other side of which is connected to line L3. Thus, whenever relay 12 is raised, the solenoid in section 32 is energized.

The normally open contacts of the switch 16 are connected in a circuit extending from line` I..1 by conductor 82 through the left-hand contacts of limit switch 62 and 'by conductors 84 and 86 to the operating coil of a holding relay 88. 'I'he relay 88 is normally initially energized by closure of the normally open limit switch 64 which when closed establishes a-circuit from line L1 through conductor 81 and conductor 86 to the coil of relay 88. The holding circuit of the latter extends from conductor 86 by conductors 90 and 82 to the right-hand contacts of limit switch 62 and thence to line L1. Thus, whenever switch 16 is depressed and the limit switch 62 is in its normally closed -position,' the relay 88 will be. raisedV and establish its holding circuit, thus RUSSUF maintaining the relay raised until the holding circuit is broken by opening of the limit switch 62. 'I'he controlled circuit of relay 88 extends from conductor 92 by a conductor 94 to the solenoid in section 30, the other side of which is connected to line L2. Thus the relay 88 when lifted energizes the solenoid in section 30.

It will be seen that the electric circuit above described operates when the starting button 68 is depressed to lift the relay 12 which establishes its own holding circuit and also establishes a. circuit from line Ll through limit switch 66, conductor 18, switch 16, conductor 14V and conductor 80 to the solenoid in section 32. This, as will be described later, causes downward movement of the piston 48 carrying the dog rod 54. During the rst part of this movement the dog 56 passes ofi from the switch 62 permitting the latter to close but not energizing the relay 88 due to the breaks in the circuit at switch 16. At some point in the mid portion of the travel the dog 58 contacts switch 64 energizing the relay 88 through conductors 81 and 86 and lifting thesame to establish its holding circuit and to establish the controlled circuit extending from line Ll through switch 62, conductors 92 and 94 to the solenoid in section 30. This, as will be later described, *l

causes the piston 48. to continue its descent at a slower or feed rate of movement. As the piston 48 approaches the bottom of its stroke the dog 60 contacts the switch 66 opening the holding circuit for relay 12 and thus deenergizing the solenoid in section 32. 'I'his causes the piston 48 to ascend, and when it reaches the top the dog 58 contacts the switch 62 opening the same and breaking the holding circuit for relay 88, thus deenergizin'g the Y, solenoid in section 30. 'I'his causes the device to come to rest. x

The internal construction of the panel 28 is illustrated at Figure 2. The port 24 in the cene' ,ter section 26 communicates by' a conduit 98 which leads to the pressure port of a pilot-V operated four-way valve generally designated as |02. The latter has tank ports |04 and |06 which connect by a conduit |08 with the port 34. One cylinder port I0 connects by a conduit ||2 with the cylinder port 38. The other cylinder port 4 connects by a conduit ||6 with a manually adjustable throttle I8.

On the opposite side the throttle communicates with the discharge chamber |20 of a hydrostatic valve |22 having an inlet port |24. The valve |22 is under the control of a piston |26 and spring |28, theright-hand face of the piston being subject to pressure in the conduit i6 through a branch conduit |30 while thelefthand face of the piston is subject to pressure in the discharge chamber |20 through a conduit |32. I'he action of the hydrostatic valve |22 and throttle I8 is such as to maintain a fixed but adjustable rate of ow therethrough independently of pressure variations by maintaining a constant pressure drop across the throttle ||8. rIIfhe inlet port |24 of the hydrostatic valve 22 connects by a conduit |34 with a conduit |36 leading to one cylinder port |38 of a pilot-operated four-way valve |40. A by-pass conduit |42 connects between conduits ||6 4and |36 and contains a check valve |44 open to free flow fro l conduit ||6 to conduit |36. f

The pressure port |46 of valve |40 connects by a conduit |48 with the port 40. The tank ports. |50 and |52 of valve |40 connect by a conduit |54 with the tank conduit |08. The other cylnder port |56 connects by a conduit |58 with a port |60 of a foot valve |62. `The latter comprises a two-land spool |64 biased to the left by a spring |66 in which position the spool blocks communication between port |60 and a port |68. The left-hand end of the valve communicates with the conduit ||2 through a branch conduit so that whenever 'pressure exists in conduit ||2 suicient to overcome the force of spring 66 the spool |64 is shifted to the right to connect the ports |60 and |68. Port |68 and the right-hand end of the valve chamber connect by a conduit |12 to the tank conduit |54.

The spools |14 and |16 of the valves |02 and |40 are adapted to be shifted by hydraulic pressurev admitted and exhausted to and from their end chambers under the control of the pilot valves which are disposed in the side sections 30 and 32. For this purpose a branch conduit |18 extends from the pressure line 98 to the opposite faces of the center section 26 and through the side sections 30 and 32 to the pressure ports |80 and |82 of solenoid-operated four-way pilot valves |84 and |86 respectively.

A cylinder port |88 of valve |84 connects, by a conduit |90 with the left-hand end chamber of the valve |40. The other cylinder port |92 connects by a conduit |94 with the right-hand end chamber of the valve |40. The upper end of the valve |84 and drain chambers |96 and |98 formed in the spool 200 connect to tank by a conduit 202 and by a central bore 204' formed in the spool 200.

The pilot valve |86 is identical in construction y. to thepilot valve |84, its corresponding parts yand 226 and have projecting stems 228 and 230 which may be lifted by the solenoids 232 and 234. Emergency manual operating stems 236 and 238 may be secured to the armatures 240 and 242 respectively for manual lifting of either solenoid in case of power failure. The solenoids may be enclosed by angle-shaped cover plates 244 and` 246.

The relative disposition of the various valves in the blocks 26, 30 and 32 is indicated in the projected views constituting Figures 3, 4, and 5. The throttle |8 may be connected to a suitable indicator handle 248 on the front of the central section. The ports 24, 34, 38 and 40 are preferably brought out to the back face of the center section 26 so that the latter may, if desired, be

mounted directly upon a machine frame having corresponding ports adapted to register therewith when the block 26 is fastened thereto.

For applications where the machine frame is not especially designed for direct mounting of the panel o n the frame, a backing plate 250 is provided for mounting the center section 26 and having cored passages therein which register with the ports in the back face of the center block 26 and lead to pipe connections 252 and 254 at one side and 256 and`258 at the other side.

Before considering the operation of the hydraulic circuit as a whole, it will be understood that whenever solenoid 232 is deenergized, pressure uid from line 98 passes through conduit |18, port |80, port |88 and conduit |90 tothe left-hand end of valve |40, shifting the latter to the right discharging oil from the right end through conduit |94, port |92, drain chamber |88, conduits 202 and |12 to tank. When solenoid 232 is energized the connections are reversed to admit pressure to the right end of valve |40 and connect the left end to tank whereby the valve shifts to the left. Identical action takes place with regard to the solenoid 234 controlling the valve |02 so that when solenoid 234 is deenergized the valve is shifted to its right-hand position and when'energized the valve is shifted tol its left-hand position.

The operation of the main hydraulic circuit may be more easily understood by reference to the simplified circuit shown in Figure 7 and the table of valve positions shown in Figure 8.. In Figure 7 the four-way valves |02 and |40 are illustrated as circles and the solenoid-operated pilot valves which shift them have been omitted,

With the valves |02 and |40 inthe position shown in the table of Figure 8 for the rapid advance function, the oil is withdrawn by the pump |0 through conduit I4 and delivered th'rough conduits I8 and 98 to port |00 of valve |02 where it is directed to port ||0 and through conduits ||2 and 42 to the head end of cylinder 46. Oil discharged from the rod end passes through conduits 44 and |48 to port |46 of valve 40 where it is delivered to port |56, through conduit |58, Valve |62, and'conduit |12 to tank. Valve |62 is open at this time because pressure is transmitted from line ||2 through conduit |10 to open the valve. The outlet path under these 'conditions is shown by the dotted arrow The circuit @just described is that established when solenoid 234 is energized andsolenoid 232 is deenergized. l'

As the piston Y48 reaches the point where'dog 58 closes limit switch 64, the solenoid 232 becomes energized as previously described and valve |40 is shifted to the position for feed as shown in Figure 8. Under these conditions the flow to the head end of the cylinder 46 is the same as before while the outlet path for uid from the rod end is now delivered from port |46 to port |38 and through conduits |36 and |34, flow controlvalve |22||8, conduit ||6, ports ||4 and |04of valve |02, conduits |08 and 36 to tank. This outlet path is indicated by the dotted arrow 2. Under these conditions the piston 48 can travel only as fast as the setting of lthe throttle ||8 dictates, andl this rate of flow is maintained by the action of the hydrostatic valve |22` independently of variations in the resisting load which the piston 48 must overcome. f

As the piston reaches its lower limit the dog 60 opens the limit switch 66, thus deenergizing the solenoid 234 and shifting the valve |02 to the position shown in Table 8 for rapid return. Under these conditions oil which is delivered bythe pump flows from port |00 toport ||4 of valve |02 through conduit ||6, check valve |44, conduits |42 and |36, ports |38 and |46 of valve |40, and conduits |48 and 44 to the rod end of cylinder 46. Fluid delivered from the head end is discharged through conduits l,42 and 2, ports ||0 and |04 of valve |02, and conduits |08 and 36 to tank. This outlet path is shown bythe dotted arrow 3. 'I'hus the piston 48 is caused to return upwardly at a rapid rate.

When the piston reaches its uppermost position the limit switch 62 is opened, thus deenergizing solenoid 232 to shift the valve |40 to the position shown for stop in Table 8. Undertheseconditions oil delivered by the pump to port |38 of valve |40 is transferred to the port 50 thereof and through conduit |54 to tank. The pump is thus by-passed through the outlet path indicated by the dotted arrow 4 at negligible pressure. It will be noted also that due to lack of pressure in line H2, the

valve |62 moves to closed position, thus preventing downward travel of the piston 48 under its gravity bias.

The present control panel is so constructed that the pilot valves and solenoids for operating the same are arranged in the two side sections 30 and 32 which may be assembled to a center section 26 of one capacity or another, thus providing a, flexible unit system wherein complete control panels for operating fluid motors of various sizes may be readily assembled from fewer standard parts than otherwise. i

Y The foot valve |62 presents the advantage that during both the rapid advance and the feed movements of the cylinder the latter is positively opened by pressure in the high side of the system and consequently there is no load imposed by the foot valve which the pump must overcome in order to move the piston 48. Thus the full capacity of the pump plus the gravity bias is available for effective work particularly during the feed portion of the cycle, and yet the valve |62 is effective to maintain the piston stationary against a gravity load of any magnitude.

The present invention has been described in a form suitable for use with a unitary power transmission system wherein a single pump feeds a single motor through the novel control panel described. It will be understood, howeve that where a single pump feeds other apparatus in addition to that controlled by the present panel or where a separate pump unloading valve is used,

it may be undesirable to unload the pump when the valves |02 and"|40 are in stop position. In such cases the valve |40 may be constructed as a three-way valve omitting the port |50. Preferably this is accomplished by substituting a different valve spool having its lands properly arranged so 'as to control ports |38, |46 and |56 in the manner disclosed but arrangedl to block port |50 in all positions. i

While the form ofembodiment of the invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted, al1 coming within the scope of the claims which follow.

What is claimed is as follows:

1. In a fluid power transmission system the combination with a source of pressure fluid of a fluid motor, fluid supply and return conduits leading from and to the source of fluid, a pair of directional control valves each independently shiftable between only two positions and connected to one of said conduits, and branch conduits connecting said valves to each other and to the motor and forming with said valves four different paths for fluid between opposite sides of said source, one of said paths providing a by-pass through both valves around the source, the other three paths providing flow to and from the motor in both directions-including two differently controlled paths between the motor and the source in one direction.

- 2. In a fluid power transmission system the combination with a source of pressure fluid of a iiuid motor, fluid supply and return conduits leading from and to the source of fluid, a pair of directional control valves each independently shiftable between only two positions and connected to one of said conduits, and branch, conduits paths for uid between opposite sides-of said 'source including at least one path extending through both valves between the motor and the f source, one of said paths providing a by-pass around the source, the other three paths providing flow to and from the motor in each direction with a flow rate controller' in one path.

3. In a iiuid power transmission sys-tem the combination with a source of pressure uid of a fluid motor, fluid supply and return conduits leading from and to the source of fluid, a pair of directional control valves each independently 'shiftable between only two positions and connec'ted to one of said "conduits, and branch conduits connecting each of said valves both to the other valve and to the motor and forming with 'said valves four different paths for uid between opposite sides of said source, one of said paths providing a bypass around the source, the other 'three paths providing ow to and from the motor in both directions including two differently controlled paths between the motor and the source in one direction, one of which extends through both valves between Athe motor and the source.

4. In a fluid power transmission system the combination with a source of pressure fluid including a pump, uid supply and return conduits leading froml and to the source, a iiuid motor, a -pair of motor conduits extending to opposite sides of the motor, a first directional control valve -having connections with 'said supply and return conduits and with one of said motor conduits, a second directional control valve having connections with the other motor conduit, with the rst valve and with at least one of said supply and return conduits, means in one of said'connections for producing a regulated'reduced rate of iiow therein, and means for shifting-each of said valves independently between either of two positions to provide operation of the'motor at one speed in either direction, at a. different speed in one direction and to stop the motor.

5. In 'a fluid power transmission system the combination with a source of pressure iiuid including a pump, uidsupply and return conduits leading from and to the source, a fluid motor, a pair of motor conduits extending to opposite sides of the motor, a rst directional control valve having connections with said supply and return conduits and with one of said motor conduits, a

vsecond directional control valve having connec-` tions with the other motor conduit, with the flrst valve and with at least one of said supply and return conduits, means in one of said connections for producing a regulated reduced rate of ow therein, and means including a pair lof yieldably biased electric operators for shifting each of said valves independently between either of two positions to provide operation of the motor at one speed in either direction, at a different speed in one direction and to stop the motor by selective energization of said electric operators.

6. In a fluid power transmission system the combination with a source of pressure fluid including a pump, fluid supply and return conduits leading from and to the source, a iiuid motor, a pair of motor conduits extending to opposite sides of the motor, a pair of directional control valves each independently movable between only two effective positions, connections between each valve and at least one of said supply and return conduits, between each valve and the other valve and between each valve and at least one of the motor conduits, and means for shifting said valves' selectivelybetween said positions to provide three diifferentoperating cir'cuitsbetween the source and the motor and a fourth valve setting in which the motor is stopped.V

'7. In a uid power transmission system the` combination with a source of pressure fluid including a pump, uid supply and return conduits leading from and to the source, a uid motor, a

pair of motor conduits'extending to opposite sides of the motor, a pair of directional control valves each independently movable between only two e'ective positions, connections between each Valve and at least one of said supply and return conduits, between each valve and the other valve and between each valve and at least one of the motor conduits, and means for shifting said valves selectively between said positions to provide three different operating circuits between the source and the motor and a fourth valve setting in which the motor is stopped, said valves and connections forming at least two fluid paths which extend between the source and one valve throughethe other valve independently of the motor.

FERRIS T. HARRINGTON. 

